Response of moderately halophilic bacterium

The aim of the present study was to investigate the response of Salinicola socius strain SMB35T cells to oxidative stress modelled by the introduction of hydrogen peroxide into the medium. It was found that when hydrogen peroxide was added to the cell suspension to a final concentration of 25 μM, a slight decrease in biomass was observed, while the addition of hydrogen peroxide to a concentration of 25 mM resulted in a significant decrease in biomass. Since a statistically significant decrease in biomass was noted upon exposure to hydrogen peroxide at a concentration of 25 mM, the amount of compatible solutes in cells of Salinicola socius strain SMB35T after exposure to hydrogen peroxide was evaluated. Cell extracts were studied by proton magnetic resonance spectroscopy. Under conditions of oxidative stress, a trend towards a decrease in the amount of ectoine was observed, and the pool of its precursor – N(4)-acetyl-L-2,4-diaminobutyrate - decreased by a factor of 2.1. Oxidative stress significantly affected the intracellular amount of glutamate; its content decreased by 5.6 times. It was found that after incubation with H2O2, the amount of alanine and valine in the cells reduced. In response to oxidative stress, a trend towards increasing trehalose content in cells was observed, but its amount was 8.7 times less than that of ectoine.